Re: question about contourf command

[Pantxo Diribarne]

Le 17/09/2018 à 19:28, Tso-Min Chou a écrit :

Hi,

You did not attache the input file so that it is impossible for us to
reproduce and eventually diagnose this origin of the issue.
Could attach 'error_demo_2.txt'?

Pantxo



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The Z output contains NaN in regions where no (x,y) pair was provided and Octave doesn't seem to handle those well.

A workaround is to replace NaN values by some value lower than the min value and and fix the countour levels by hand. Something like

data = "" ;  % read file 

x = data(:,1); 

y = data(:,2); 

z = data(:,3);

[X,Y] = meshgrid(sort(x),sort(y));

Z = griddata(x,y,z,X,Y,'linear');

figure (1)
minz = min (Z(:));
maxz = max (Z(:));
Z(isnan (Z)) = minz - (maxz - minz) /2;

[~, h] = contourf(X,Y,Z, linspace (minz, maxz, 10));

Pantxo

error_demo_2.txt
Description: Text document